Analysis of Relative Scent Intensity, Volatile Compounds and Gene Expression in Freesia “Shiny Gold”

Abstract

Scent is one of the most important economic traits in <i>Freesia hybrida</i>. "Shiny Gold", a popular cultivar in South Korea, is widely cultivated for its scent. The relative scent intensity of "Shiny Gold" was approximately 16% higher in full-bloomed flower when compared to the yellow bud stage, while tissue-specifically, tepals showed higher intensity in electronic-nose (e-nose) analysis. E-nose analysis also showed that the scent intensity of "Shiny Gold" was higher and lower than "10C3-424" and "10C3-894", respectively, and was similar to "Yvonne". These results correlated to those of the olfactory tests. In total, 19 volatile compounds, including linalool, β-ocimene, D-limonene, trans-β-ionone were detected in gas chromatography-mass spectrometry analysis. Among these, linalool was the major volatile compound, accounting for 38.7% in "Shiny Gold". Linalool synthase and <i>TPS</i> gene expression corresponded to the scent intensity of the four cultivars, with the lowest expression in the "10C3-424". <i>TPS 2</i>, <i>TPS 3</i>, <i>TPS 5</i>, <i>TPS 6</i> and <i>TPS 8</i> were highly expressed in both bud and flower in "Shiny Gold", while the expression of <i>TPS 4</i> was lower, relative to other <i>TPS</i> genes in both the flowering stages. These results may aid in enhancing scent composition in <i>Freesia</i> cultivars using marker-assisted selection.